Retrodiscal approach of lumbar epidural block.

Objective: To compare the technical strengths and weaknesses between retrodiscal (RD) and conventional subpedicular (SP) approaches of transforaminal epidural block (TF-EPB).

Method: Sixty-one patients with L5 radiculopathy who planned to undergo TF-EPB were consecutively enrolled as study subjects. Subjects were randomly assigned to one of two groups. For the RD approach, the positioning of the patient and the C-arm were similar to that for lumbar discography. We compared the pattern of dye spreads, the frequency of complications during the procedures, and the effect of the pain block 2 weeks after the procedure between the two groups.

Results: For the RD group (n=24), the contrast dye diffused around the L5 and S1 nerve roots in 16 cases (67%), but it diffused around only the L5 root in 27 cases (73%) in the SP group (n=37) (p<0.05). Two weeks after the procedure, the visual analogue scale (VAS) decreased by the same amount in both groups (RD group: 3.1±1.6, SP group: 3.2±2.6). Symptoms of nerve root irritation occurred in 1 case of the RD group and in 10 cases of the SD group (p<0.05).

Conclusion: The RD approach was as efficient as the SP approach for temporary diagnostic relief and offered considerable advantages, such as lower nerve root irritation possible lower risk of vascular injection. Thus, it could be a useful technique when a herniated disc segment is stuck or when the foraminal stenosis is severe.